1. Field of the Invention
This invention generally relates to computer component mounting systems, and more particularly to a shock and acoustic isolation mount for a computer component. Computer components include computer disk drives, compact disk players, and other devices that attach to the support structure of a computer system.
2. Description of the Related Art
Computers systems are often subjected to mechanical shock and vibration. Shock and vibration may occur during handling and shipping. Also, shock and vibration may be caused by environmental and user factors. Computer systems in tower enclosures may be subjected to severe shock if the tower topples. Small computers and portable computers are often subjected to severe handling shocks. Vibration may be transmitted to a computer system from the outside environment or vibration may be transmitted internally within the computer system from a computer component.
Some components of a computer system are unaffected by shock and vibration. Other components, such as disk drives, may be damaged or destroyed by shock and vibration. Most disk drives have read/write heads mounted on the ends of lightweight arms. The heads are positioned adjacent to the surface of the disk. Shock or vibration of the disk drive housing may cause a head to contact the surface of the disk. Such contact may cause permanent and irreparable damage to the disk. Less severe shock and vibration to a disk drive over a period of time may cause deficiencies in disk drive performance. The performance deficiencies may include difficulty and slowness of data access. A shock to a computer system may result in the generation of vibration of the exterior of the computer system. The vibration may be transmitted throughout the computer system. Such vibration is often referred to as xe2x80x9cshock response ringing.xe2x80x9d
Many computer components rigidly mount to a support structure within a computer system. When the computer enclosure experiences shock or vibration, the shock or vibration may be transmitted directly to rigidly mounted computer components. Many modern hard drives have threaded mounting holes on opposite lateral sides of the cover. Such hard drives may be rigidly mounted to the computer chassis by screws or other fasteners.
Rigidly mounting a component in a computer system may cause acoustic problems such as structure-borne noise. Structure-borne noise in a computer system typically originates in the mechanical vibration of a component. The vibration typically propagates through solid structures, such as fasteners and the chassis, to the exterior of the computer system. The vibration may energize a large exterior area of the computer system, and the large area may radiate sound in the manner of a sounding or resonating board. Using vibration dampers and isolators between the component and the structure may reduce structure-borne noise caused by the component.
A computer system may be subjected to vibration from an external source or an internal source. If the frequency of the vibration is close to the resonance frequency of structures within the computer system, the vibration energy transmitted throughout the computer system may increase. Such an effect is often referred to as xe2x80x9cvibration resonance amplification.xe2x80x9d Vibration resonance amplification may result in the generation of loud noise from a computer system. Vibration resonance amplification may also damage components within a system. Loud noise and component damage may be caused by coupling vibratory components to the exterior of a computer system even without any resonance effects. Vibration dampers and isolators may change the resonant frequencies of structures within a computer system and damp vibrations transmitted to or from an isolated component.
Systems for isolation mounting a component in a computer system include rubber grommet isolation systems, rigid foam isolation systems, and loose elastomer sheet systems. Rubber grommet isolation systems typically include four molded grommets and a set of custom fasteners. U.S. Pat. No. 4,821,368, issued to Albrecht, and incorporated by reference as if fully set forth herein, describes an eccentric grommet used for mounting a hard disk to a computer system support structure. U.S. Pat. No. 5,644,472, issued to Klein, and incorporated by reference as if fully set forth herein, describes a rigid foam isolation system for a computer system. A component carrier is fabricated from a vibration damping material such as a urethane foam. Cavities in the foam material accommodate components of the computer system. Loose elastomer sheet systems are used in some portable computers. Elastomer sheets trap the hard disk against the computer enclosure.
The system described herein includes an isolation mount for mounting a computer component, such as a hard disk, to a computer structure. The isolation mount may inhibit external shock and vibration from reaching the component. The isolation mount may also prevent vibration of the component from being transmitted to the computer structure. The system may provide shock isolation, vibration isolation, and acoustic isolation of a component.
In one embodiment, isolators fit over, onto, or around posts mounted on opposite side walls of the computer component housing structure. The posts may be part of a bracket or brackets that fasteners attach to pre-set mounting holes in the side walls of the computer component housing. The isolators fit within sockets attached to the computer structure. The sockets may be part of a bracket or brackets that fasteners attach to the computer structure.
In an alternate embodiment, the isolators fit over, onto, or around posts attached to the computer structure. The posts may be part of a bracket or brackets that fasteners attach to the computer structure. The isolators typically fit within sockets attached to the computer component housing. The sockets may be part of a bracket or brackets that fasteners attach to preset mounting holes or openings in the side walls of the computer component housing.
The support position of the computer component is not limited by the position of pre-set mounting holes within the computer component housing. The posts and sockets on the brackets may be positioned at locations that conform to available space within a computer system enclosure.
The outside surfaces of the isolators may be approximately the same size or slightly larger than the inner surfaces of the sockets into which the isolators fit, thereby forming a frictional fit between the isolators and the sockets when the isolators are positioned within the sockets. The isolators may be formed of a material with high damping characteristics. The material may be a low stiffness, foamed material, such as a urethane foam. The damping characteristics tend to suppress vibration resonance amplification and shock response ringing. The use of low stiffness foamed elastomers as isolators provides a relatively low pre-load force between the computer component and the computer system structure. The relatively low pre-load force and the damping characteristic of the isolators tends to enhance or cause acoustic isolation, which helps to attenuate structure-borne acoustic noise caused by the computer component.
The isolators allow a more full use of available sway space to absorb shock motions. Use of available sway space is desirable in handling drops and system topples. The more full use of available sway space is an improvement over previously used grommets and rigid foam designs which are too rigid to permit large internal motions. The sway space and isolation performance in different directions of motion may be tailored to system need. For example, if the computer system is likely to be subjected to drops, the mounting posts may have extended horizontal surfaces to more effectively inhibit and damp motion caused by vertical forces transmitted to the isolation mounts as a result of the computer system being dropped.
Computer components, such as disk drives, often generate heat during use. For many disk drives, the primary heat transfer surfaces are the top and bottom surfaces of the disk drive. The isolation mount contacts the computer component at relatively small contact areas. Typically, the contact areas are on the sides of the computer component, away from the component""s primary heat transfer surfaces. The small contact area is an improvement over the rigid foam and loose-sheet isolation systems. The small contact area allows free flow of air around the computer component for cooling purposes. As such, an additional heat sink for the computer component may not be necessary.
The parts that comprise the isolation mount are typically formed from inexpensive materials. The isolation mount may not require the fabrication of special fasteners. Generally, grommet isolation systems require the fabrication of special fasteners. The isolators of the isolation mount may be fabricated from sheet stock urethane foam. The post brackets and socket brackets may be formed of plastic or sheet metal. The fasteners may be screws, rivets or other attachment means. A resulting isolation mount made from the individual parts is generally sturdy, durable, light weight, simple, efficient, reliable and inexpensive; yet the isolation mount is also easy to manufacture, install, maintain and use.